6v vs 12v battery question

[Cdash]

I have two battery questions that I can't find answers to. I'm hoping that the questions are not too stupid.

1. Amp-hour ratings - when I look at battery specs, I see different amp-hour ratings for different periods of time for the same battery, but when people talk about batteries, they only mention amp-hours. What time period from the battery spec charts is commonky used?

2. For 6v batteries, I understand that I'd need two hooked in series to make it 12v. If I'm am looking at a single 6V battery that is 100 amp-hours (made up number) when I hook up two of them in series to make a 12V system, do I have 100 amp-hours at 12v, or would I have 200 amp-hours? Wasn't sure if amperage gets cut in half because voltage doubles....

Thanks for the help!

[RJsfishin]

I suggest you fix what really is broke !!
Blaming the batteries sure ain't gonna fix it.
Optima ????? That would be the last choice of any serious dry camper.

[jake2250]

Let me throw this out there,, went from two deep cycle interstate 12v group 27's to two Costco 6V 220 AH golf cart batteries,, maybe three years old,, not allot of use because we boondock 60 % of the time and only for five days max,, Lately have been only out three times this year and batteries have been home on a Schuamker battery tender for two months at a time and a month off, They never fell below 12.7,, I am headed to the coast tomorrow for three days, tested the heater because temps might drop into the high thirties,, not freezing, heater drew the batts down to 12.1 before I shut it off, and recovered at 12.3, When I hooked them up they were 13.4, Not happy!! water level was topped off (just below the ring)and I have 200 watts of solar, I will bring along my group 31 trolling motor Wal Mart battery just in case!! I am leaning towards a set of Trojan T105s if these don't cut it. My thought is the heater will cut in a few times while we sleep, I have a Gen and will charge daily, I have never seen these deplete so quickly,, If they **** out next week, Its off to High dollar quality, if that does not work,, back to 12v Optima's!!
Had one on my PUP (Yellow Top) Couldn't kill it!!

[Bobbo]

wolfe10 wrote:
But, the vast majority of 6 VDC golf cart batteries are in the 220 amp-hr range. So a pair wired in series is 220 amp-hrs @ 12 VDC.

My 6 volt batteries are 208 amp-hrs each, so I have 2*208 = 208 amp-hrs. (He was out of the 232 amp-hr batteries and I needed them that day.)

FYI - This is NOT a made up number.

[Cdash]

Not confused. Got my answer. Double the amp-hours for two 12's, don't double for two 6's, 20 hour drawdown is commonly used for the amp-hours rating and some people can't handle numbers I pull out of my rear for super easy math.

[RJsfishin]

Whats really amazing is that the "Battery Goddess" hasn't come in w/ a big long drawn out post that would really break everyone's mind !

[wolfe10]

Almot wrote:

bfast54 wrote:

Because it would seem that the MADE UP NUMBER....of "100".X 2 would be 200.
But ..thats not the way it works in 12 volt.

It is exactly the way it works, if they are 12V batteries and the goal is a 12V total bank. 100x2=200 AH.

But, since the OP asked about 2*6V @(made up number)100 AH wired in such a way as to make it 12V bank, it would 2*100 AH = 100 AH total capacity.

You either add volts (in series wiring), or amps and AH (in parallel). I guess, he is already confused enough, let's not mud the waters more yet 🙂

Absolutely correct math.

But, the vast majority of 6 VDC golf cart batteries are in the 220 amp-hr range. So a pair wired in series is 220 amp-hrs @ 12 VDC.

[Almot]

bfast54 wrote:

Because it would seem that the MADE UP NUMBER....of "100".X 2 would be 200.
But ..thats not the way it works in 12 volt.

It is exactly the way it works, if they are 12V batteries and the goal is a 12V total bank. 100x2=200 AH.

But, since the OP asked about 2*6V @(made up number)100 AH wired in such a way as to make it 12V bank, it would 2*100 AH = 100 AH total capacity.

You either add volts (in series wiring), or amps and AH (in parallel). I guess, he is already confused enough, let's not mud the waters more yet 🙂

[korbe]

lc0338 wrote:
Yes, but he could have at least made up a credible one. My goodness....

Cdash, don't be surprised when you get some stupid answers on this forum. Some never read the original posters question.

My goodness folks, it was a joke. You people need to loosen up a bit. Gosh. I read and understood the complete post. My oh my. :R

[lc0338]

Yes, but he could have at least made up a credible one. My goodness....

Cdash, don't be surprised when you get some stupid answers on this forum. Some never read the original posters question.

[korbe]

doughere wrote:

korbe wrote:

2oldman wrote:
"(made up number)"

Yes, but he could have at least made up a credible one. My goodness....

The batteries on the sub I was on were about 10,000 Amp-hours, would that be a more credible number?

Yep. Just a little test to see if the little emoticons are really needed around here. They sure are. Just a little holiday humor. 🙂 😉 :B

[doughere]

korbe wrote:

2oldman wrote:
"(made up number)"

Yes, but he could have at least made up a credible one. My goodness....

The batteries on the sub I was on were about 10,000 Amp-hours, would that be a more credible number?

[wa8yxm]

When wiring batteries in series.
1: They must be indentical Same size, make, model, age, and so on.
2: YOu add volts. NOT capacity (So in your example of two 100 amp hour batteries in series you get 100 amp hours.. at 12 volts)

You should treat each pair of six volt batteries EXACTLY as you would a single 12 volt battery .. For that is what they are.

Wiring 12 volt batteries in parallel
1: THey need NOT be identical.. but it is not a good idea to mix different technoligies (IE: AMM and Flooded wet) Not that some do not go it with good results.

2: You add CAPACITY, not voltage,, So a Group 24 (75ha) and a group 31 (130) give you about 205...

But wait there is more.

Six volt batteries are usualy DEEP CYCLE, designed to go down to half full before serious damage sets in

MARINE/deep cycle are NOT DEEP CYCLE (note case) you really should not take them to half. 70 percent perhaps (I do not know for sure what the lower state of charge is) but not half.

Starting batteries and MARINE without mention of Deep cycle are even worse

[2oldman]

korbe wrote:

2oldman wrote:
"(made up number)"

Yes, but he could have at least made up a credible one. My goodness....

Oh for shame..

[bfast54]

ok...How about 2000 amp hr ..?????:h

Because it would seem that the MADE UP NUMBER....of "100".X 2 would be 200.
But ..thats not the way it works in 12 volt.

Good Question -----I believe.